1. Field of the Invention
The present invention relates to a method for manufacturing split probes used as probes and nano-forceps in scanning of semiconductors.
2. Description of Related Art
A method for manufacturing micro-forceps using a focused ion beam device on the tip of a probe of a microcantilever used as a probe microscope probe has recently drawn attention (refer to patent document 1).
A split probe of the related art is shown in FIG. 5. FIG. 5(a) is a side view of a microcantilever, where numeral 8 is a cantilever probe. FIG. 5(b) is the upper surface of the microcantilever. FIG. 5(c) is an enlarged view of portion 7 of FIG. 5(b). In a typical method taken as a specific procedure for manufacturing microforceps, the whole of a probe 8 is irradiated with a beam that has been finely focused by a focused ion beam device without tilting a sample, an image for the whole of the scanned probe 8 is obtained, and a processing position is decided. A process of forming a channel 9 by making insulating locations on the cantilever that are to be severed face the beam from a center part of the tip of the probe on the microcantilever and then irradiating and scanning just a specific two locations is then carried out. The tip of the probe 8 is then split into a two-electrode structure where each electrode is electrically conductive.
“Patent Document 1”
Japanese Patent Laid-open Publication No. 2001-252900 ([0048], FIG. 10, FIG. 11).
However, in the related processing method, 1) The radius of curvature of the cantilever probe tip is small at 100 nm or less. It is therefore difficult to determine the central part of the cantilever probe tip in methods for specifying processing position using an image for the whole tip taken from above, and splitting the true center into two is therefore difficult. 2) Because the whole of the probe is processed using the same focused ion beam current, a relatively large focused ion beam current is used in the processing, and the channel processing width therefore becomes large. A large processing channel means that the distance between the divided electrodes is large, and it is difficult to obtain the desired electrode pitch when using the split probe as microscopic electrodes as is. Further, for example, during the assembly of, for example, carbon nanotubes, gaps open up between fellow carbon nanotubes so that, for example, a voltage applied during electrostatic driving has to be made high. 3) When an extremely narrow range of a cantilever probe is irradiated and scanned in order to decide processing position using the focused ion beam current amount using 2), the etching speed is fast because the ion beam current is large. This causes damage to the tip of the probe of the cantilever greater than that which is tolerated, so as to bring about problems such as, for example, localized peeling of conductive coats and non-uniformity of electric field, and localized increases in electrical resistance.